Responses of banana fruit to treatment with 1-methylcyclopropene

Experiments were conducted to determine levels of 1-methylcyclopropene (1-MCP) exposure needed to prevent ethylene-stimulated banana fruit ripening, characterise responses of ethylene-treated fruit to subsequent treatment with 1-MCP, and to test effects of subsequent ethylene treatment on 1-MCP-treated fruit softening. Fruit softening was measured at 20°C and 90% relative humidity. One hour exposure at 20°C to 1000 nl 1-MCP/l essentially eliminated ethylene-stimulated ripening effects. Exposure for 12 h at 20°C to just 50 nl 1-MCP/l was similarly effective. Fruit ripening initiated by ethylene treatment could also be delayed with subsequent 1-MCP treatment. However, 1-MCP treatment only slowed down ripening of ethylene-treated fruit when applied at 1 day after ethylene and was ineffective when applied 3 or 5 days after ethylene treatment. The ripening response of fruit treated with 1-MCP and subsequently treated with ethylene varied with interval time between 1-MCP and ethylene treatments. As time increased, the response of 1-MCP-treated fruit to ethylene was enhanced. Responses to 0.1, 1, 10 or 100 µl ethylene/l concentrations were similar. Enzyme kinetic analysis applied to 1-MCP effects on ethylene-induced softening of banana fruit suggested that 1-MCP inhibition is by noncompetitive antagonism of ethylene binding.     

Effect of 1-methylcyclopropene on postharvest physiological changes of ‘Zaohong’ plum

Plum is a highly perishable fruit and postharvest fruit softening limits its shelf life. The aim of this work was to study the specific effects of 1-methylcyclopropene (1-MCP) treatment on physiological changes in ‘Zaohong’ plums. Plums were treated with 500 nL L⁻¹ 1-MCP at 20°C for 18 h followed by 20°C storage. The results showed that 1-MCP treatment significantly reduced endogenous ethylene production and the activities of ethylene biosynthetic enzymes’ (1-aminocyclopropane-1-carboxylic acid synthase, ACS and 1-aminocyclopropane-1-carboxylic acid oxidase, ACO) in plum fruit during storage when compared with untreated fruit. Although 1-MCP treatment inhibited ethylene production and 1-aminocyclopropane-1-carboxylic acid (ACC) accumulation, it did not inhibit the accumulation of N-malonyl-ACC (MACC). Higher firmness was also found in 1-MCP-treated plums than in controls. During storage, superoxide anion (O₂^−·) and hydrogen peroxide (H₂O₂) levels decreased in 1-MCP-treated fruit. 1-MCP treatment also regulated superoxide dismutase (SOD) and catalase (CAT) activities during storage. Xylanase activity was upregulated while activities of polygalacturonase (PG), pectin methyl esterase (PME) and cellulase enzymes in the fruit were downregulated by 1-MCP treatment. In conclusion, 1-MCP might be a potent compound for extending both storage period and shelf life of ‘Zaohong’ plums by suppressing ethylene biosynthesis, regulating cell wall degradation enzymes and reducing fruit softening.     

Effects of 1-MCP and exogenous ethylene on fruit ripening and antioxidants in stored mango

Mango (Mangifera indica L. cv. Tainong) fruits were harvested at the green-mature stage in Hainan and air-freighted to the laboratory at Peking. The fruits were treated with either 1 μl l⁻¹ 1-MCP or 5 μl l⁻¹ ethylene for 24 h and stored at 20°C for up to 16 days. 1-MCP maintained fruit firmness, whereas exogenous ethylene decreased fruit firmness. Exogenous ethylene accelerated the increase in ethylene and 1-aminocyclopropane-1-carboxylate (ACC) oxidase, whereas 1-MCP reduced both. Exogenous ethylene stimulated and 1-MCP inhibited the production of H₂O₂ of mango fruit during storage. Ascorbic acid was maintained at a high concentration in 1-MCP-treated fruit but was low in ethylene-treated fruit. 1-MCP inhibited activities of antioxidant enzymes including catalase, superoxide dismutase and ascorbate peroxidase. These results suggest that 1-MCP could play a positive role in regulating the activated oxygen metabolism balance. Baogang Wang and Jianhui Wang contributed equally to this work.     

Effects of Chilling Temperatures on Ethylene Binding by Banana Fruit

Banana fruit are highly susceptible to chilling injury during low temperature storage. Experiments were conducted to compare ethylene binding during storage at chilling (3 and 8 °C) versus optimum (13 °C) temperatures. The skins of fruit stored at 3 and 8 °C gradually darkened as storage duration increased. This chilling effect was reflected in increasing membrane permeability as shown by increased relative electrolyte leakage from skin tissue. In contrast, banana fruit stored for 8 days at 13 °C showed no chilling injury symptoms. Exposure of banana fruit to the ethylene binding inhibitor 1-methylcyclopropene (1 l l^-1 1-MCP) prevented ripening. However, this treatment also enhanced the chilling injury accelerated the occurrence of chilling injury-associated increased membrane permeability. ¹⁴C-ethylene release assay showed that ethylene binding by banana fruit stored at low temperature decreased with reduced storage temperature and/or prolonged storage time. Fruit exposed to 1-MCP for 12 h and then stored at 3 or 8 °C exhibited lower ethylene binding than those stored at 13 °C. Thus, chilling injury of banana fruit stored at low temperature is associated with a decrease in ethylene binding. The ability of tissue to respond to ethylene is evidently reduced, thereby resulting in failure to ripen.     

Papaya fruit softening, endoxylanase gene expression, protein and activity

Papaya ( Carica papaya L.) cell wall matrix polysaccharides are modified as the fruit starts to soften during ripening and an endoxylanase is expressed that may play a role in the softening process. Endoxylanase gene expression, protein amount and activity were determined in papaya cultivars that differ in softening pattern and in one cultivar where softening was modified by the ethylene receptor inhibitor 1-methylcyclopropene (1-MCP). Antibodies to the endoxylanase catalytic domain were used to determine protein accumulation. The three papaya varieties used in the study, 'Line 8', 'Sunset', and 'Line 4-16', differed in softening pattern, respiration rate, ethylene production and showed similar parallel relationships during ripening and softening in endoxylanase expression, protein level and activity. When fruit of the three papaya varieties showed the respiratory climacteric and started to soften, the level of endoxylanase gene expression increased and this increase was related to the amount of endoxylanase protein at 32 kDa and its activity. Fruit when treated at less than 10% skin yellow stage with 1-MCP showed a significant delay in the respiratory climacteric and softening, and reduced ethylene production, and when ripe was firmer and had a 'rubbery' texture. The 1-MCP-treated fruit that had the 'rubbery' texture showed suppressed endoxylanase gene expression, protein and enzymatic activity. Little or no delay occurred between endoxylanase gene expression and the appearance of activity during posttranslational processing from 65 to 32 kDa. The close relationship between endoxylanase gene expression, protein accumulation and activity in different varieties and the failure of the 1-MCP-treated fruit to fully soften, supported de novo synthesis of endoxylanase, rapid posttranslation processing and a role in papaya fruit softening.     

Effect of 1-MCP and low-temperature storage on postharvest conservation of camu–camu

Camu–camu, a native fruit from the Amazon region, is a rich source of bioactive compounds. However, its intense metabolic activity and high-water content limit the fruit’s postharvest storage and marketing. The aim of this study, conducted in two parts, was to evaluate the effects of 1-MCP and storage temperature on the physiology and postharvest preservation of camu–camu fruit. In part 1 of the study, fruit harvested at maturity stage 3 were divided into groups: control, 1-methylcyclopropene (1-MCP; 900 nL L^?1; 12 h) and ethylene (1000 µL L^?1; 24 h) and were stored at 22?±?1 °C and 85?±?5% RH for 9 days. In part 2, fruit harvested at maturity stage 3 were stored at 5, 10, 15, 20, or 25?±?1 °C and 85?±?5% RH for 9 days. During storage, fruit were evaluated daily for decay, mass loss, respiratory activity, and ethylene production, and every 3 days they were evaluated for peel color, pulp firmness, soluble solids content, total titratable acidity, ascorbic acid, total chlorophyll, and total anthocyanins. Fruit treated with 1-MCP exhibited delayed ripening due to lower metabolic activity, as evidenced by delay to softening, reduced mass loss and no decay. Storage at 5 °C prevented ethylene production, mass loss, color changes, and maintained pulp firmness, while did not affect soluble solids content. The results indicated that storage of camu–camu fruit at 5 °C or at 25 °C following application of 900 nL L^?1 1-MCP were effective strategies to delay ripening and maintain fruit quality up to 9 days.     

Effect of Abscisic Acid on Banana Fruit Ripening in Relation to the Role of Ethylene

Abstract The role of abscisic acid (ABA) in banana fruit ripening was examined with the ethylene binding inhibitor, 1-methylcyclopropene (1-MCP). ABA (0, 10⁻⁵, 10⁻⁴, or 10⁻³ mol/L) was applied by vacuum infiltration into fruit. 1-MCP (1 μL/L) was applied by injecting a measured volume of stock gas into sealed glass jars containing fruit. Fruit ripening, as judged by ethylene evolution and respiration associated with color change and softening, was accelerated by 10⁻⁴ or 10⁻³ mol/L ABA. ABA at 10⁻⁵ mol/L had no effect. The acceleration of ripening by ABA was greater at 10⁻³ mol/L than at 10⁻⁴ mol/L. ABA-induced acceleration of banana fruit ripening was not observed in 1-MCP treated fruit, especially when ABA was applied after exposure to 1-MCP. Thus, ABA's promotion of ripening in intact banana fruit is at least partially mediated by ethylene. Exposure of ABA-treated fruit to 0.1 μL/L ethylene for 24 h resulted in increased ethylene production and respiration, and associated skin color change and fruit softening. Control fruit (no ABA) was unresponsive to similar ethylene treatments. The data suggest that ABA facilitates initiation and progress in the sequence of ethylene-mediated ripening events, possibly by enhancing the sensitivity to ethylene. Received 29 January 1999; accepted 16 January 2000     

The effects of ethylene concentration in controlled atmosphere storage of tomatoes

Previous studies have demonstrated that mature green tomatoes can be stored for up to 10 wk at 12. 5°C, 93–95% r.h. in a controlled atmosphere (CA) containing 5% CO ₂ , 5% O₂ and 90% N ₂ , and will then ripen satisfactorily in air at 20°C. The effects of different concentrations of ethylene between <0.1 and 30 μl/litre in this storage atmosphere on ripening changes and fruit quality after 5 wk CA storage and a further 8 or 9 days ripening in air were investigated using cv. Sonatine glasshouse tomatoes. Maintaining ethylene concentrations in the storage atmosphere to.1 plllitre resulted in poor and uneven ripening of the tomatoes after storage, and increased their susceptibility to infection by Botrytis cinerea and Penicillium spp. Fruit previously stored in atmospheres containing 5 to 30 μl/litre ethylene were significantly softer after ripening than tomatoes stored in lower ethylene concentrations. Overall, the best results in terms of fruit quality (colour, firmness) and a low incidence of fungal infection were achieved with 1–3 μl/litre ethylene. The practical problems in achieving and maintaining optimum conditions, including the correct ethylene level, in CA storage of tomatoes are also discussed.     

Softening response of banana fruit treated with 1-methylcyclopropene to high temperature exposure

Elevated temperatures experienced by harvested fruit can modulate theirripening. Moreover, heat treatments can be applied to reduce susceptibility tolow temperature disorders and to help control pests and diseases. Theethylene-binding inhibitor 1-methylcyclopropene (1-MCP) was used to investigatethe ethylene-mediated softening response of banana fruit exposed to elevatedtemperatures. A preliminary experiment was conducted to determine levels ofhightemperature (30–50°C) imposed for a short periodof time that did not cause skin scald. The softening response of Williamsbananafruit treated with 1-MCP at various temperatures and durations wascharacterisedin subsequent experiments. Exposure of fruit to hot air for 60 minat 45°C or for 30 min at50°Ccaused 30–40% peel scald. The peel was not visibly damaged forfruit treated at 40°C for up to 60 min.Softening of fruit treated with 1-MCP for 12 h at25°Cand then held for 7 days at 30, 35 or 40°C wasinhibited in proportion to increasing concentration over the range 0.01–1l/l 1-MCP. However, softening was progressively enhanced withincreasing holding temperatures from 30–40°Cand/or time from 1–7 days, although fruit treated with the higher 1-MCPconcentrations of 1 and 10 l/l were comparatively lessresponsive to heat. Although banana fruit held at30–40°Cdid not de-green, their increased softening at elevated temperatures andinhibition of this response by 1-MCP suggest that heat enhances synthesis ofnewethylene sites which mediated banana fruit softening.     

Ozone-induced inhibition of kiwifruit ripening is amplified by 1-methylcyclopropene and reversed by exogenous ethylene

Background

Understanding the mechanisms involved in climacteric fruit ripening is key to improve fruit harvest quality and postharvest performance. Kiwifruit (Actinidia deliciosa cv. ‘Hayward’) ripening involves a series of metabolic changes regulated by ethylene. Although 1-methylcyclopropene (1-MCP, inhibitor of ethylene action) or ozone (O₃) exposure suppresses ethylene-related kiwifruit ripening, how these molecules interact during ripening is unknown.

Results

Harvested ‘Hayward’ kiwifruits were treated with 1-MCP and exposed to ethylene-free cold storage (0?°C, RH 95%) with ambient atmosphere (control) or atmosphere enriched with O₃ (0.3?μL?L^??1) for up to 6?months. Their subsequent ripening performance at 20?°C (90% RH) was characterized. Treatment with either 1-MCP or O₃ inhibited endogenous ethylene biosynthesis and delayed fruit ripening at 20?°C. 1-MCP and O₃ in combination severely inhibited kiwifruit ripening, significantly extending fruit storage potential. To characterize ethylene sensitivity of kiwifruit following 1-MCP and O₃ treatments, fruit were exposed to exogenous ethylene (100?μL?L^??1, 24?h) upon transfer to 20?°C following 4 and 6?months of cold storage. Exogenous ethylene treatment restored ethylene biosynthesis in fruit previously exposed in an O₃-enriched atmosphere. Comparative proteomics analysis showed separate kiwifruit ripening responses, unraveled common 1-MCP- and O₃-dependent metabolic pathways and identified specific proteins associated with these different ripening behaviors. Protein components that were differentially expressed following exogenous ethylene exposure after 1-MCP or O₃ treatment were identified and their protein-protein interaction networks were determined. The expression of several kiwifruit ripening related genes, such as 1-aminocyclopropane-1-carboxylic acid oxidase (ACO1), ethylene receptor (ETR1), lipoxygenase (LOX1), geranylgeranyl diphosphate synthase (GGP1), and expansin (EXP2), was strongly affected by O₃, 1-MCP, their combination, and exogenously applied ethylene.

Conclusions

Our findings suggest that the combination of 1-MCP and O₃ functions as a robust repressive modulator of kiwifruit ripening and provide new insight into the metabolic events underlying ethylene-induced and ethylene-independent ripening outcomes.

     

Effect of diazocyclopentadiene on tomato ripening

Diazocyclopentadiene (DACP) in the presence of fluorescent light delayed ripening of tomato fruits treated at the mature green (no visible red) stage. At 25 °C, ripening was delayed 10 days if DACP [185 µl/1 (gas)] was added as a single treatment and longer if DACP was added intermittently at 5-day intervals. The addition of 1000 µl/1 ethylene following DACP and light treatment did not hasten ripening. Little ripening delay was noted for fruit + DACP held in darkness. Tomatoes covered with aluminum foil so as to exclude light but not light-activated DACP, showed ripening inhibition. Apparently, the light-activated product from DACP is stable long enough to diffuse into fruit held in darkness. After an initial inhibition, ethylene production was greatly increased in tomatoes treated with DACP. Tomatoes with or without DACP treatment were held either in air or 5% O₂/95% N₂ for 12 days then treated with ethylene. Treatment with 5% O₂ alone delayed ripening when compared to air alone, however, both groups reached 80% red color by 18 days. DACP treated fruit, whether held in air or 5% O₂, still were green after 18 days and only approached 80% red color after approximately 27 days. Thus, 5% oxygen did not appear to slow the reversal of DACP inhibition of ripening.     

Effect of ethylene and 1-methylcyclopropene on chlorophyll catabolism of broccoli florets

Branchlets of broccoli (Brassica oleracea L.) were used to examine ethylene-stimulated chlorophyll catabolism. Branchlets treated with: 1) air (CK); 2) 1 µL·L^–1 1-methylcyclopropene (1-MCP) for 14 hr at 20 °C; 3) 1000 µL·L^–1 ethylene (C₂H₄) for 5 hr at 20 °C; or 4) 1-MCP then C₂H₄, were stored in the dark at 20 °C for up to 3 d. Chlorophyll (Chl) content and branchlet hue angle decreased during the storage period and 1-MCP treatment delayed this change. Chl degradation in broccoli was accelerated by exposure to C₂H₄, especially for Chl a. Prior treatment with 1-MCP prevented degreening stimulated by C₂H₄. Lipoxygenase activity was not altered by any of the treatments, however, 1-MCP with or without ethylene resulted in reduced activity of chlorophyllase (Chlase) and peroxidase (POD). Exposure to C₂H₄ stimulated Chlase activity and extended the duration of high POD activity. Treatment with 1-MCP followed by C₂H₄ resulted in reduced POD activity and delayed the increase in Chlase activity. The results suggest chlorophyll in broccoli can be degraded via the POD – hydrogen peroxide system. Exposure to C₂H₄ enhances activity of Chlase and extends the duration of high POD activity, and these responses may accelerate degreening. Treatment with 1-MCP delays yellowing of broccoli, an effect that may be due to the 1-MCP-induced reduction in POD and Chlase activities.     

乙烯诱导西瓜果实的水渍化败坏

为了研究乙烯在西瓜(Citrullus lanatusThunb.Mansfeld)果实水渍化败坏过程中的作用,先将果实在5μL/L 1-甲基环丙烯(1-MCP)气体中处理18 h,然后在50 μL/L乙烯和20℃温度下贮藏.西瓜果实对乙烯处理的最初反应表现为胎座组织的电导率和游离汁液增加,同时出现组织软化和水渍化.水渍化的症状最初在靠近花萼端的内果皮中发生,在乙烯处理的第2天开始出现,ACC合成酶(ACS)和ACC氧化酶(ACO)的活性明显提高.1-MCP单独处理不产生任何明显的作用,但是会完全抑制外源乙烯诱导的水渍化败坏.没有经过乙烯处理的西瓜果实,贮藏2 d以后出现呼吸强度和乙烯释放量的高峰,10 d以后水渍化现象也零星出现.这些结果和1-MCP的预防效果说明,西瓜果实的水渍化败坏是一种由乙烯诱导的衰老现象.     

1-MCP对香蕉果实货架期的影响

香蕉果实经乙烯利处理后当天和1d分别用1-甲基环丙烯(1-MCP)处理,果实色泽转变、软化及淀粉降解均受到明显抑制,货架期延长5d以上;而乙烯利处理后贮放2d或3d再用1-MCP处理已失去对果实后熟的抑制作用。香蕉果实经1-MCP处理后在常温下贮藏11d完全恢复对乙烯敏感。     

Benefits of ethylene removal during apple storage

The potential use of an ethylene absorbent in controlled atmosphere storage of two varieties of apple has been investigated. With Golden Delicious, the rise in ethylene concentration during controlled atmosphere storage can be delayed for about 40 days but not prevented by inclusion of potassium permanganate in the storage container. But with Bramley's Seedling, potassium permanganate can delay ethylene accumulation for over 200 days. Ethylene treatment of Bramley's Seedling in a flowing stream of 5% CO₂:3% O₂:92% N₂ caused accelerated softening, accumulation of α-farnesene and earlier onset of superficial scald. Use of potassium permanganate to remove ethylene during storage in static controlled atmosphere conditions retarded all three processes in Bramley's Seedling kept in 5% CO₂:3% O₂ and in 9% CO₂:12% O₂. However, in one experiment, ethylene removal in 5% CO₂:3% O₂, led to external and internal symptoms of CO₂ damage. A subsequent investigation of the combined effects of harvest date, store temperature and ethylene removal in 5% CO₂:3% O₂ did not show any damage or accumulation of succinic acid which is known to be involved in CO₂ injury. This experiment revealed that ethylene removal could be successfully accomplished on Bramley fruit harvested up to a month after the usual date and little α-farnesene accumulated in this fruit. Nevertheless scald did develop on late picked fruit and this raises doubts about the causal role of farnesene in scald.     

Delay ripening of ‘Qingnai’ plum (Prunus salicina Lindl.) with 1-methylcyclopropene

‘Qingnai’ plum fruit were treated with 0, 250, 500 or 1000 nL L⁻¹ of 1-methylcyclopropene (1-MCP) for 6 h and stored at 20 °C. The fruit firmness, peel color, chlorophyll content, titratable acidity (TA), respiration rate and ethylene production, chlorophyllase, pectin methylesterase (PME) and polygalacturonase (PG) activities were monitored during postharvest ripening of ‘Qingnai’ plums. ‘Qingnai’ plums without 1-MCP treatment soften very rapidly at room temperature after harvest, showing a continuing decrease in hue angle, chlorophyll content, TA and increase in chlorophyllase, PME and PG activities during postharvest storage. In contrast, the 1-MCP-treated fruits showed reduced ethylene production and respiration rate and delayed softening, which was associated with the reduction in the activity of PME and PG. The 1-MCP treatment also significantly inhibited the chlorophyllase activity and peel color development in ‘Qingnai’ plums during postharvest ripening at 20 °C. These results suggest that 1-MCP treatment may be useful for maintaining the fruit quality and extending the postharvest shelf-life of ‘Qingnai’ plums.     

1-甲基环丙烯采后处理对樱桃番茄果实成熟过程的影响

研究了不同浓度(0、0.035、0.07和0.11μL/L)的乙烯受体竞争性抑制剂1-甲基环丙烯(1-MCP)采后处理对绿熟期樱桃番茄的乙烯合成、果实软化、果实色素(叶绿素、茄红素、β-胡萝卜素)含量消长的影响.0.07 μL/L及其以上浓度的1-MCP降低了前期乙烯合成,同时推迟了乙烯释放高峰,但0.035 μL/L浓度的1-MCP处理并不能抑制内源乙烯合成.1-MCP显著延迟了果实软化和叶绿素降解,但并不影响这两个过程的启动.茄红素合成的启动和积累均受到了1-MCP抑制,而1-MCP并不推迟β-胡萝卜素合成的启动,只抑制其积累.这些结果提示了乙烯调节成熟生理过程的不同机制.对于绿熟期的樱桃番茄,0.07～0.11μL/L的1-MCP是实用的有效处理浓度.1-MCP有效浓度可能用于了解果实的乙烯受体水平和乙烯敏感性.     

Low-temperature-modulated fruit ripening is independent of ethylene in 'Sanuki Gold' kiwifruit

Fruit ripening in response to treatments with propylene, 1-methycyclopropene (1-MCP), and low temperature was characterized in 'Sanuki Gold' kiwifruit, Actinidia chinensis Planch. Propylene treatment immediately induced rapid fruit softening, increased AC-PG (polygalacturonase) and AC-EXP (expansin) mRNA accumulation, and stimulated an increase in the soluble solid concentration (SSC) and a decrease in titratable acidity (TA). After 3?d exposure to propylene, ethylene production and AC-PL (pectate lyase) mRNA accumulation were observed. 1-MCP treatment after 24?h exposure to propylene eliminated AC-PG mRNA accumulation and suppressed continued changes in SSC and TA. Application of 1-MCP at the start of the treatment, followed by continuous propylene exposure, markedly delayed fruit softening, and the expression of the cell wall-modifying genes, and changes in the SSC and TA, indicating that kiwifruit become insensitive to ethylene at least for 3?d following 1-MCP exposure. Surprisingly, significant fruit softening, mRNA accumulation of AC-PG, AC-PL, and AC-EXP, and decreased TA were observed without ethylene production in intact fruit stored at low temperature for 1 month, but not in fruit stored at room temperature. Repeated 1-MCP treatments (twice a week) failed to inhibit the changes that occurred in low temperature storage. These observations indicate that low temperature modulates the ripening of kiwifruit in an ethylene-independent manner, suggesting that kiwifruit ripening is inducible by either ethylene or low temperature signals.